Production of detergent compositions

ABSTRACT

A detergent powder containing a synthetic detergent active compound and an organic detergency builder is prepared by forming an aqueous slurry of detergent ingredients containing not more than 40 percent by weight of the slurry of water in a pressurised vessel at a temperature of from about 125*C to 180*C and subsequently spraying the slurry into a gas stream at a temperature of from about 100* to 250*C. The process is particularly useful for producing powders of high organic content, for which there can be a fire or explosion hazard in using conventional spray-drying processes at higher temperatures. The process can also give significant economic benefits.

[11] 3,844,969 Oct. 29, 1974 1 PRODUCTION OF DETERGENT COMPOSITIONS [75] Inventors: Joseph John Griffiths; Raymond John Wilde, both of Wirral, England [73] Assignee: Lever Brothers Compnay, New

York, NY.

22] Filed: July 6,1971

21 App1.No.: 160,157

[30] Foreign Application Priority Data July 10, 1970 Great Britain 33718/70 [56] References Cited UNITED STATES PATENTS 2,606,156 8/1952 Davis 252/550 2,798,544 7/1957 Davis 159/48 2,940,935 6/1960 Reich et al 252/109 3,355,390 11/1967 Behrens 252/527 3,459,670 8/1969 Carter 252/99 3,515,672 6/1970 Reinish et al.

3,580,852 5/1971 Yang 252/135 3,635,829 1/1972 Yang 252/526 3,692,685 9/1972 Lamberti et a1, 252/89 3,708,436 1/1973 Thompson et al. 252/527 Primary Examiner-Leon D. Rosdol Assistant Examiner-4. E. Willis A ttbrheyT/i gent, or Firm Richard AI G aither, Esq., Melvin H. Kurtz, Esq., Arnold Grant, Esq.

[57] ABSTRACT A detergent powder containing a synthetic detergent active compound and an organic detergency builder is prepared by forming an aqueous slurry of detergent ingredients containing not more than 40 percent by weight of the slurry of water in a pressurised vessel at a temperature of from about 125C to 180C and subsequently spraying the slurry into a gas stream at a temperature of from about 100 to250C. The process is particularly useful for producing powders of high organic content, for which there can be a fire or explosion hazard in using conventional spray-drying processes at higher temperatures. The process can also give significant economic benefits.

2 Claims, No Drawings PRODUCTION OF DETERGENT COMPOSITIONS The invention relates to the production of detergent compositions, and in particular to the production of compositions in particulate or powder form by spraying an aqueous slurry of detergentingredients into a drying gas stream.

Detergent powders are commonly made by a process in which an aqueous slurry is sprayed into a chamber through which a gas stream is passed, so that the water in the slurry is evaporated. The aqueous slurry may be at a relatively high temperature to that of the gas, in which case flash evaporation of the water in the slurry occurs during the process, which is sometimes referred to as spray-cooling. More often, the aqueous slurry is at a relatively low temperature and the gas stream is heated to a higher temperature, which process is generally termed spray-drying. Forcon'venience, the term spray-drying" is used hereinafter to encompass all powder-forming processes in which'aqueous slurries are sprayed into drying gas streams.

Conventional spray-drying processes are not readily applicable to the production of detergent powders of high organic content, due to the tire or explosion hazard if the powder is overheated in the presence of oxygen, which is usually available as the drying gas is normally air. Moreover the move to decrease the content of phosphates, particularly condensed phosphate detergency builders such as sodium tripolypl'iosphate, in de tergcnt compositions, because of suggestions that such use of phosphates contributes to eutrophication has generally tended to increase the organic content of detergent powders.

The possible organic replacements for condensed phosphate detergency builders which have been proposed hitherto include so-called polye'lectroly'te builders, such as sodium polyacrylate, sodium po'lymaleate and copolymers thereof such as sodium copolyethylene-maleate. certain oxidised polysaccharides and non-polymeric builders such as sodium oxydiacetate, sodium carboxymethyloxysuccinate and sodium nitrilotriacetate. Other preferred, organic detergency builders are the water-soluble salts of dicarboxylic acids of the formula R.CH(COOH)(CH COOH, where n is O or 1 and R is a primary or secondary straight chain alkyl or alkenyl group containing from to carbon atoms, which are described in the complete specification of our co-pending UK patent application No. 37961/68. The preferred dicarboxylates are sodium alkenyl succinates, which can be prepared by hydrolysis and neutralisation of alkenyl succinic anhydrides which are obtained by reaction between maleic anhydride and olefins.

The amounts of detergency builders in detergent compositions may be up to as much as 50 percent by weight, in which case the total organic content of detergent powders may sometimes be as high as 80 percent by weight. when the organic content of the detergent active compounds and optional additives, such as hydrotropes, lather boosters, anti-redeposition agents and fluorescent agents are taken into consideration. Under these circumstances, when the powders contain more than about 50 percent of organic matter, there is a substantial risk of fire or explosion if the powders-are overdried and overheated during their preparation in conventional spray-drying processes.

According to the present invention, a detergent powder containing a synthetic detergent active compound and an organic detergency builder is prepared by forming an aqueous slurry of detergent ingredients containing not more than about 40 percent by weight of the slurry of water in a pressurised vessel at a'temperature of from about 125to 180C and subsequently spraydrying the slurry in a stream of gas at a temperature of from about l00 to 250C.

Using this process, it is possible to produce detergent powders under conditions which in the spray-drying step are not so severe as to involve any substantial fire or explosion hazard. Moreover, the invention can give valuable economic benefits in detergent powder propractical amount of water, which is not more than about 40 percent by weight, preferably less than 30 percent by weight, of the slurry. The water content can be as low as about 20 percent by weight of the slurry, under optimum circumstances, as explained hereinafter.

The condition employed in spray-drying are preferably as mild as possible, commensuaate with obtaining a satisfactory powder production rate, in order to decrease any fire risk to a minimum, particularly with the powders containing the higher amounts of organic matter. The gas temperature in the spray-drying step is preferably from about 150 to about 200C. The spraydrying operation is preferably conducted under conditions so as to obtain in a single operation a free-flowing powder, but if desired, for example to increase the throughput of a spray-drying tower, the conditions of spray-drying may be modified so that the powder initially produced is still moist, and the excess water is removed in a-subsequent drying operation, for example by using afluidised bed inwhich additional drying gas is passed through the powder, either in a batchwise or continuous process, or by using a pneumatic drier in which the powder is dried whilst being conveyed by a hot gas.

It will be appreciated that it is essential to prepare the slurry under pressure in a closed vessel because of the elevated temperatures used. The pressure also serves to transfer theslurry after its preparation to the spraydryer and to atomise the slurry for spraying into the gas. Generation of the pressure in the vessel is preferably accomplished by live steam, or as this tends to raise the water content of the slurry, by air pressure, or by a combination of both. The pressure in the vessel should'be such as to give at the spraying jet a pressure of from about 40 to p.s.i.g. (2.8 to 4.9 kilogram/sq.cm) but it can go higher, for example up to about p.s.i.g. (7.0 kilogram/sq.cm), above which there is no significant benefit and the cost of the equipment increases excessively. In practice pressures in the vessel of up to about -200 p.s.i.g. are generally used.

The process of the invention is only applicable to the production of detergent powders 'of which the ingredients are available in a suitably dry form which enables the production of the aqueous slurries containing not more than about 40 percent by weight of water. In respect of ingredients which in the powder are in the form of salts of organic acids, as is commonly the case for organic detergency builders and anionic detergent active compounds, the organic acid or its anhydride is preferably neutralised with an alkaline material such as sodium hydroxide in the slurry: otherwise, if the salt is preformed it generally incorporates too much water to enable the slurry to be made with the required amount of less than 40 percent of water. This is because neutralisation of the acids outside the slurry generally requires excess water to control the heat of neutralisation and to make the product pumpable, and drying the solution of neutralised product to a powder is not economical. However, if a detergency builder salt or an anionic detergent active compound is available in sufficiently dry form, for example as a powder or flake, it can to advantage be used directly in slurry-making.

In the preferred form of process according to the invention, the main ingredients, apart from the organic detergency builder in acid or anhydride form, are admixed and heated to a temperature of from about 100C to 140C. The precursor of the detergency builder is then added whereupon it is neutralised, and hydrolysed if necessary, in the slurry and the heat of neutralisation causes the temperature and pressure to rise to the desired figures for spray-drying. This process may be operated on a batch-wise or continuous basis.

The process of the invention is of particular interest for the preparation of detergent powders incorporating alkyl and alkenyl succinates as detergency builders. These materials can be prepared readily in anhydride form and can be added in that form to the aqueous slurry where hydrolysis and neutralisation takes place to form the desired water-soluble salts. Some analogous compounds such as the alkyl thio and alkyl oxysuccinates can be used similarly.

Other detergency builders which can be used in the process of the present invention include, for example the salts of a-sulphonated fatty acids, for example or-sulphonated hardened tallow fatty acids, higher alkane disulphonate and sulphinate-sulphonates, and soaps, all of which act as detergency builders in detergent compositions by forming insoluble calcium salts; water-soluble salts of organic acids including oxydiacetic acid, oxydisuccinic acid, carboxymethyloxysuccinic acid, hydrofuran tetracarboxylic acid, and homologues and analogues of these materials, oxidised polysaccharides in which the anhydroglucose rings are opened to form dicarboxyl units as described in the complete specifications of our UK patent applications Nos. 4I5l2/69 and 40100/79; and polyelectrolyte detergency builders such as sodium polyacrylate and sodium polymaleatc and copolymers thereof such as sodium copolyethylene maleate. but it should be noted that with some polyelectrolytes there may be a tendency to decarboxylation at the higher temperatures. Many other suitable organic detergency builders are available and described in the literature, for example in Surface Active Agents and Detergents by Schwartz, Perry & Berch.

In addition to the organic detergency builders mentioned above, the detergent compositions commonly incorporate one or more detergent active compounds, together with the usual optional additives. The synthetic detergent active compounds are preferably anionic detergent active compounds, which are readily available and relatively cheap, and mixtures thereof. These compounds are usually water-soluble alkali metal salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 car bon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of such synthetic anionic detergent active compounds are sodium and potassium alkyl (Cg-C20) benzene sulphonates, particularly sodium linear secondary alkyl (C -C benzene sulphonates; sodium and potassium salts of fatty acid amides of methyl taurine; alkane sulphonates such as those derived by reacting alphaolefins (C -C with sodium bisulphite and those derived by reacting paraffins with S0 and Cl and then hydrolysing with a base to produce a random sulphonate; and olefin sulphonates, which term is used to cover the material made by reacting olefins, particularly alpha-olefins, with 50;, and then neutralising and hydrolysing the reaction product.

it should be noted that some anionic detergent active compounds such as alkyl and alkyl ether sulphates tend to hydrolyse at the higher temperatures which can be used in the present process.

If desired, nonionic detergent active compounds may also be used. Examples include the reaction products of alkylene oxides, usually ethylene oxide, with alkyl (C -C phenols, generally 5 to E0; i.e., 5 to 25 units of ethylene oxide per molecule; the condensation products of aliphatic (c -C lalcohols with ethylene oxide, generally 6 to E0, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other non ionic detergent active compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.

Mixtures of detergent active compounds, for example mixed anionic or mixed anionic and'nonionic compounds may be used in the detergent compositions, particularly to impart thereto controlled low sudsing properties. This is particularly beneficial for compositions intended for use in suds-intollerant automatic washing machines.

Amounts of amphoteric or zwitterionic detergent active compounds, for example betaines, sulphobetaines and hydroxyalkylmethyl taurines, can also be used in the compositions of the invention, but this is not normally desired due to their relatively high cost. if any amphoteric or zwitterionic detergent active compounds were used it would generally be in small amounts in compositions based on the much more commonly used anionic or nonionic detergent active compounds.

Many other suitable detergent active compounds are commercially available and more fully described in the literature, for example in Surface Active Agents and Detergents" by Schwartz, Perry and Berch.

The amount of the synthetic detergent active compound or compounds used is generally in the range of from about 10 to percent, preferably about 15 to 3O percent, by weight of the compositions, depending on the desired properties.

Optional additives to detergent compositions made according to the invention include lather boosters such as coconut ethanolamide, hydrotropes such as sodium toluene sulphonate, inorganic salts such as alkaline silicates, sodium carbonate, sodium chloride and sodium sulphate, anti-redeposition agents such as sodium carboxymethylcellulose, fabric softening agents, fluorescent agents, colourants, germicides, fungicides, perfumes, enzymes and chemical bleaching agents such as sodium perborate and peracid precursors. Some of the additives, particularly oxygen-liberating bleaching agents such as sodium perborate, are usually added to the detergent powders after their production by spraydrying.

The invention is illustrated by the following Examples in which parts and percentages are by weight.

Example 1 A detergent slurry was prepared by admixture of the following ingredients in a stirred reaction vessel at a temperature of 150C and under a pressure of 40 to 50 psig (2.8 to 3.5 kg/sq.cm).

ingredient Percentage hexadecenyl-succinic anhydride 7 33.7 sodium hydroxide (50% aqueous solution) 18.7 alkaline silicate (50% aqueous solution) 11.8 sodium dodecyl benzene sulphonate 25.8

flake (8071 active content. obtained by sulphonation of Oronite 1060) sodium sulphate 4.5 sodium toluene sulphonate 1.0 coconut cthanolamide 3.2 sodium carboxymethylcellulose 0.5 fluorescers 0.6

Example 2 The procedure of Example 1 was repeated except that the formulation of the aqueous slurry was as follows:

ingredient Percentage hexadecenyl-succinic anhydride 27.3 dodecyl benzene sulphonic acid (obtained 19.4

by sulphonation of DOBS 055) alkaline silicate 13.3 sodium sulphate 5.5 sodium toluene sulphonate 0.9 sodium carboxymethyl cellulose 0.45 coconut ethanolamide 2.8 water 19.3 fluorescent agents 0.35 sodium hydroxide (flake) 10.7

The slurry was sprayed at a temperature of 150C through an one-eighth inch (3.2 mm) spray nozzle into a stream of air at a temperature of 200C and a flow rate of lbs (45.4 Kg) per minute, to produce a powder of 9 percent moisture and 72 percent organic matter content, which was again crisp and free-flowing.

Example 3 An aqueous slurry was made by admixture of the following ingredients in a pressure vessel in which the temperature was raised to 160C.

sodium dodecyl benzene sulphonate 1' (obtained from B085 055 dodecyl benzene) (507: paste) sodium silicate (50% aqueous solution) sodium carboxymethyl cellulose sodium ethylene diamine tetraacetate fluorescent agents sodium sulphate The slurry having a water content of about 32 percent was sprayed at 55 p.s.i.g. (3.9 Kg./sq. cm.) through an one-eighth inch (3.2 mm) jet nozzle into a countercurrent air stream at a temperature of 200C to give a free-flowing powder containing about 59 percent of organic matter and 5 percent of water.

Example 4 A detergent slurry was prepared at C and under 60 psig (4.2 Kg/sq.cm) by admixture of sodium dodecyl benzene sulphonate and disodium oct'adecane-lsulphonate-Z-sulphinate with minor additives to give a water content of about 28 percent. The slurry was spray-dried though a one-eighth inch (3.2 mm) jet into a countercurrent air stream at 200C to form a sluggish-flowing powder of the following formulation:

ingredient Percentage sodium dodecyl benzene sulphonate 17.8

(prepared from DOBS 055) disodium alkane (Coil-l.sulphonate'Z-suIphinate 44.5 alkaline silicate 7 sodium carboxymethyl cellulose 0.5 fluorescent agents 0.9 inorganic salts (mainly sodium sulphate) 13.8 water 1.5.5

Example 5 ingredient Percentage sodium dodecyl benzene sulphonate 20 sodium coconut soap 55 alkaline silicate 10 sodium sulphate 8.5 sodium carboxymethyl cellulose 0.5 fluorescent agents 1.0 water 5.0

- In a comparative test, a detergent powder was prepared to the same formulation by a spray-drying process in which the slurry was prepared with a water content of about 40 percent and at a temperature of 90C. The slurry was pumped to a spray drying tower at 400 p.s.i.g. and sprayed into air at 300C to give a free flowing powder, but of low density. In this case, the amount of heat required to evaporate the water and thereby form the powder was increased by about 50 percent.

What is claimed is:

1. A process for the preparation of a detergent powder having an organic content of from 50-80 percent, said organic content consisting essentially of a synthetic anionic, nonionic, zwitterionic or amphoteric detergent active compound which is present in an amount of from about 10-50 percent by weight of the total composition, an organic detergency builder which is present in an amount of from about 27 to about 50 percent by weight of the total composition, said builder being selected from the group consisting of a-sulpho- 8 nated fatty acids, higher alkane disulfonates and sulfinate-sulfonates, soaps, sodium polyacrylate, sodium polymaleate and sodium copolyethylene maleate, oxidised polysaccharides, sodium oxydiacetate, sodium carboxymethyloxysuccinate, sodium nitrilotriacetate, the water soluble salts of dicarboxylic acids of the formula R.CH(COOH) (CH ),,.COOH when n is 0 or 1 and R is a primary or secondary straight chain alkyl or alkenyl group containing from 10 to 20 carbon atoms and mixtures thereof, which process comprises forming an aqueous slurry of detergent ingredients containing from about 20 to about 40 percent by weight of the slurry of water in a pressurised vessel at a temperature of from about C to C, and subsequently spray drying the slurry in a stream of gas at a temperature of from about 100C to about 250C.

2. A process according to claim 1, wherein the water content of the slurry is not more than about 30 percent by weight. 

1. A PROCESS FOR THE PREPARATION OF A DETERGENT POWDER HAVING AN ORGANIC CONTENT OF FROM 50-80 PERCENT, SAID ORGANIC CONTENT CONSISTING ESSENTIALLY OF A SYNTHETIC ANIONIC, NONIONIC ZWITTERNIONIC OR AMPHOTERIC DETERGENT ACTIVE COMPOUND WHICH IS PRESENT IN AN AMOUNT OF FROM ABOUT 10-50 PERCENT BY WEIGHT OF THE TOTAL COMPOSITION, AN ORGANIC DETERGENCY BUILDER WHICH IS PRESENT BY WEIGHT IN AN AMOUNT OF FROM ABOUT 27 TO ABOUT PERCENT BY WEIGHT OF THE TOTAL COMPOSITION SAID BUILDER BEING SELECTED FROM THE GROUP CONSISTING OF A-SULPHONATED FATTY ACIDS, HIGHER ALKANE DISULFONES AND SULFINATE-SULFONATES SOAPS, SODIUM POLYACRYLIC, SODIUM POLYMALALEATE AND SODIUM COPOLYMETHYLENE MALEATE, OXIDIZED POLYSACCHARIDES, SODIUM OXYDIACETTE, SODIUM CARBOXYMETHYLOXYSUCCINATE, SODIUM NITROLTRIACETATE, THE WATER SOLUBLE SALTS OF DICARBOXYLIC ACIDS OF THE FORMULA R.CH(COOH)(CH2)N.COOH WHEN N IS 0 OR1 AND R IS A PRIMARY OR SECONDARY STRAIGHT CHAIN ALKYL OR ALKENYL GROUP CONTAINING FROM 10 TO 20 CARBON ATOMS AND MIXTURES THEREOF, WHICH PROCESS COMPRISES FROMING AN AQUEOUS SLURRY OF DETERGENT INGREDIENTS CONTAINING FROM ABOUT 20 TO ABOUT 40 PERCENT BY WEIGHT OF THE SLURRY OF WATER IN A PRESSURIZED VESSEL AT A TEMPERATURE OF FROM ABOUT 125*C TO 180*C AND SUBSEQUENTLY SPARY-DRYING THE SLURRY IN A STREAM OF GAS AT A TEMPERATURE OF FROM ABOUT 100*C TO ABOUT 250*C.
 2. A process according to claim 1, wherein the water content of the slurry is not more than about 30 percent by weight. 